Coherent single-photon absorption by single emitters coupled to 1D nanophotonic waveguides

TL;DR

This paper develops a time-dependent theory to analyze and enhance the efficiency of single-photon absorption by a single emitter in a 1D waveguide, achieving over 70% excitation with optimized configurations.

Contribution

It introduces a comprehensive dynamic model for single-photon absorption in waveguides and proposes a terminated waveguide and dispersion engineering to significantly improve absorption efficiency.

Findings

Maximum atomic excitation of ~40% with Gaussian wavepackets.

Enhanced excitation exceeding 70% with waveguide termination.

Improved absorption efficiency by 4% through dispersion engineering.

Abstract

We study the dynamics of single-photon absorption by a single emitter coupled to a one-dimensional waveguide that simultaneously provides channels for spontaneous emission decay and a channel for the input photon. We have developed a time-dependent theory that allows us to specify any input single-photon wavepacket guided by the waveguide as initial condition, and calculate the excitation probability of the emitter, as well as the time evolution of the transmitted and reflected field. For single-photon wavepackets with a gaussian spectrum and temporal shape, we obtain analytical solutions for the dynamics of absorption, with maximum atomic excitation $\thicksim 40%$. We furthermore propose a terminated waveguide to aid the single-photon absorption. We find that for an emitter placed at an optimal distance from the termination, the maximum atomic excitation due to an incident single-photon wavepacket can exceed 70%. This high value is a direct consequence of the high spontaneous emission $\beta$-factor for emission into the waveguide. Finally, we have also explored whether waveguide dispersion could aid single-photon absorption by pulse shaping. For a gaussian input wavepacket, we find that the absorption efficiency can be improved by a further 4% by engineering the dispersion. Efficient single-photon absorption by a single emitter has potential applications in quantum communication and quantum computation.